The present invention relates to a circuit board and a method for making a multi-layer electrical circuit board and, more particularly, to a method for making a multi-layer electrical circuit board having at least one electrically conductive portion or xe2x80x9cviaxe2x80x9d which traverses through the multi-layer electrical circuit board.
Multi-layer circuit boards allow electrical components to selectively and operatively populate opposed surfaces of each board (or other respective interior portions of each of the boards), thereby desirably allowing each of the electrical circuit boards to contain a relatively large amount of electrical components which efficiently and densely populate the respective boards. It is desirable to allow each of the component-containing surfaces or portions of a created and/or formed electrical circuit board to communicate and/or to be interconnected, thereby allowing the contained electrical components to cooperatively and selectively form one or more desired electrical circuits. This desired communication and/or interconnection typically requires the use of shared electrical ground planes, the transmittal of power and/or control type signals between each of the component containing surfaces or board portions, and/or the selective connection of the contained components.
This desired communication and/or component interconnection typically requires that one or more holes be drilled through each of the circuit boards, thereby creating at least one xe2x80x9cthrough holexe2x80x9d or xe2x80x9cviaxe2x80x9d which traverses each of the opposed component containing surfaces and the various interior circuit board portions. Such drilling is undesirable since it is relatively time consuming, costly, potentially causes damage to significant numbers of the formed electrical circuit boards requiring these circuit boards to be destroyed, and requires costly and inefficient electroless and/or electrolytic plating of the formed holes or xe2x80x9cviasxe2x80x9d.
While some attempts have been made to obviate the need for such plating, such as by the use of a conductive epoxy within each of the drilled holes, these attempts have not produced reliable electrical interconnections and these produced interconnections are not typically adapted to allow the communication of electrical power signals between the board surfaces and the formed apertures also do not securely and reliably receive a component.
Further, it is desirable to form xe2x80x9ccrossover type circuitsxe2x80x9d upon one or more selected surfaces and/or within certain component containing portions of the formed circuit board in order to allow multiple levels of circuits and/or electrical interconnections to be formed upon a single board surface or within a certain component containing portion of the circuit board, thereby desirably increasing the amount of electrical circuits which may be created upon and/or within the created circuit board.
The crossover circuits which are formed by these prior methodologies do not typically and efficiently accommodate certain desirable circuit board interconnection processes and/or schemes such as and without limitation, the use of relatively heavy wire (e.g., using aluminum wire having a diameter of about five thousandths of an inch to about twenty thousandths of an inch) or the direct connection of components to a surface of the board.
There is therefore a need to provide a method for producing a multi-layer electrical circuit board which overcomes some or all of the previously delineated drawbacks of prior circuit boards and/or circuit board forming methodologies, which selectively allows for the efficient creation of interconnection portions which traverse the various layers of the formed electric circuit board assembly, and which further allows for the efficient and selective formation of crossover members and/or circuits which desirably accommodate diverse types of circuit interconnection processes and/or schemes and which allow for the selective creation of a relatively large amount of circuits.
It is a first object of the present invention to provide a method for producing a multi-layer electrical circuit board which overcomes some or all of the previously delineated drawbacks of prior multi-layer electrical circuit board forming methodologies and techniques.
It is a second object of the invention to provide a method for producing a multi-layer electrical circuit board which overcomes some or all of the previously delineated drawbacks of prior multi-layer electrical circuit board forming methodologies and techniques, which allows for the selective, efficient, and reliable formation of electrically conductive interconnection portions which selectively and cooperatively allow for the communication and/or electrical connection by and between various electronic components, and which allows for the creation of crossover members and/or circuits, effective to increase the electrical circuit density within these formed boards.
It is a third object of the invention to provide a method for producing a multi-layer electrical circuit board which overcomes some or all of the previously delineated drawbacks of prior multi-layer electrical circuit board forming methodologies and techniques and which allows for the selective and efficient formation of crossover members which are adapted to accommodate a wide variety of components and component interconnection techniques and/or assemblies.
According to a first aspect of the present invention, a method for making a multi-layer electric circuit board is provided. The method includes the steps of providing a first member having a first and a second surface; selectively removing portions of the first surface of the first member, thereby creating at least a first and a second depressed portion within the first surface of the first member while allowing a third portion of the first surface to remain intact; filling the first and second depressed portions with a first material; applying a second material to the third portion; attachably overlaying a second member upon the third portion and upon the first material; forming at least one aperture within the second member and at least one aperture within the second surface of the first member; filling the at least one aperture within the second surface of the first member and filling the at least one aperture within the second member with the first material; applying the second material to the second surface of the first member and to the second member; connecting a third member to the first member and connecting a fourth member to the second member, thereby forming a multi-layer circuit assembly having an interconnection portion which extends through the formed multi-layer circuit and which is cooperatively formed by the third portion and by the second, third, and fourth members.
According to a second aspect of the present invention, a circuit assembly is provided. The circuit assembly is made by the process of providing a first electrically conductive member; selectively etching the first electrically conductive member, thereby creating at least one protuberance; placing a certain material upon said first electrically conductive member; and attaching a second electrically conductive member to the at least one protuberance and attaching a third electrically conductive member to the first electrically conductive member, thereby forming a multi-layer circuit board and causing the at least one protuberance to extend through the multi-layer circuit board.
According to a third aspect of the present invention, a circuit assembly is provided. The circuit assembly is made by the process of providing a first member; selectively etching the first member, thereby causing the first member to have at least one protuberance; providing a plurality of conductive members; and attaching the plurality of conductive members to the first member, thereby creating a multi-layer circuit assembly while causing the at least one protuberance to interconnectingly extend through the multi-layer circuit assembly.
These and other objects, aspects, and advantages of the present invention will become apparent upon reading the following detailed description in combination with the accompanying drawings.